Method and network node for FFT based power detection for LBT in LTE LAA

Abstract

A method performed in a radio access node includes the radio access node receiving a data for transmission to a second radio access node over a communication channel having an unlicensed spectrum. The method further includes, in response to receiving the data, the radio access node receiving a channel measurement signal over the communication channel. The method further includes the radio access node performing an N-point Fast Fourier Transform (FFT) on the channel measurement signal to produce a frequency domain signal with N bins. The method further includes the radio access node performing a power measurement on the frequency domain signal. The method further includes the radio access node analyzing the power measurement of the frequency domain signal. The method further includes the radio access node transmitting the data based on the analysis of the power measurement.

The invention claimed is: 
     
       1. A method performed in a first wireless communication device (WCD), the method comprising:
 the first WCD receiving data for transmission to a second WCD over a communication channel having an unlicensed spectrum; 
 the first WCD receiving a channel measurement signal over the communication channel; 
 the first WCD performing an N-point Fast Fourier Transform (FFT) on the channel measurement signal to produce a frequency domain signal with N bins;
 wherein the N-point FFT is performed a predetermined number of times, and the frequency domain signal is an average of the predetermined number of times the N-point FFT is performed; 
 
 the first WCD performing a power measurement on the frequency domain signal; 
 the first WCD analyzing the power measurement of the frequency domain signal; and 
 after the first WCD analyzes the power measurement of the frequency domain signal, the first WCD transmitting the data to the second WCD based on the analysis of the power measurement, wherein the data is transmitted in response to determining that the analyzing of the power measurement on the frequency domain signal indicates that a predetermined number of bins corresponding to a channel is clear of transmissions. 
 
     
     
       2. The method of  claim 1 , wherein the analyzing the power measurement of the frequency domain signal includes performing a statistical analysis process is applied to the frequency domain signal. 
     
     
       3. The method of  claim 1 , wherein the predetermined number of bins corresponding to a channel is clear of transmissions when the power of the predetermined number of bins is below a predetermined threshold. 
     
     
       4. The method of  claim 1 , wherein the N-point FFT is performed in parallel for a plurality of channels. 
     
     
       5. The method of  claim 1 , wherein the first WCD is a radio base station, a femto base station, a mobile station, a CPE (Customer premises Equipment), an access point, or a radio relay. 
     
     
       6. The method of  claim 1 , wherein the first WCD operates according to one of the following standards: Wifi, LTE, LTE-U, LTE-LAA, MuLTEfire, WiMAX, Bluetooth, and ZigBee. 
     
     
       7. A first wireless communication device (WCD) comprising:
 a processor; 
 a non-transitory computer readable medium coupled to the processor, said computer readable medium containing instructions executable by the processor, wherein the first WCD is operative to: 
 receive data for transmission to a second WCD over a communication channel having an unlicensed spectrum; 
 receive a channel measurement signal over the communication channel; 
 perform an N-point Fast Fourier Transform (FFT) on the channel measurement signal to produce a frequency domain signal with N bins,
 wherein the N-point FFT is performed a predetermined number of times, and the frequency domain signal is an average of the predetermined number of times the N-point FFT is performed; 
 
 perform a power measurement on the frequency domain signal; 
 analyze the power measurement of the frequency domain signal; and 
 after analyzing the power measurement of the frequency domain signal, transmit to the second WCD the data based on the analysis of the power measurement, wherein the data is transmitted in response to determining that the analyzing of the power measurement on the frequency domain signal indicates that a predetermined number of bins corresponding to a channel is clear of transmissions. 
 
     
     
       8. The first WCD of  claim 7 , wherein the analyzing the power measurement of the frequency domain signal includes performing a statistical analysis process is applied to the frequency domain signal. 
     
     
       9. The first WCD of  claim 7 , wherein the predetermined number of bins corresponding to a channel is clear of transmissions when the power of the predetermined number of bins is below a predetermined threshold. 
     
     
       10. The first WCD of  claim 7 , wherein the N-point FFT is performed in parallel for a plurality of channels. 
     
     
       11. The first WCD of  claim 7 , wherein the first WCD is a radio base station, a femto base station, a mobile station, a CPE (Customer premises Equipment), an access point, or a radio relay. 
     
     
       12. The first WCD of  claim 7 , wherein the first WCD operates according to one of the following standards: Wifi, LTE, LTE-U, LTE-LAA, MuLTEfire, WiMAX, Bluetooth, and ZigBee.